Bc Board Descriptions - Sony TRINITRON BVM-14G1A Operation And Maintenance Manual

1-17. G2 Control
Of the G2 R signal, G2 G signal, and G2 B signal, the signal
with the lowest voltage is input to IC705 (1/2), compared
with the reference voltage (G2 REF) to become the G2 CON-
TROL signal, and output from pin 10B of CN1 to the E
board through the C board to control the G2 voltage of the
CRT.
2. ABL, Overload Detection
At IC901 (1/2), the ABL voltage and reference voltage (–1
Vdc) are compared. Normally, the ABL voltage is above –1
Vdc and therefore the output level of IC901 (1/2) is "High".
If the ABL voltage goes down and it becomes less than –1
Vdc, the CONT. BRT will be therefore controlled so that this
voltage will become –1 Vdc (constant). The output leve of
IC901 (1/2) is set to lower than the CONTRAST voltage and
therefore the OVERLOAD signal and therefore the OVER-
LOAD signal output from IC904 (1/2) becomes "High".
3. Control Circuit
The SUB CPU (IC902) performs serial communication with
system controller using the three signals MISO, MOSI, and
SCLK, and outputs the control signal according to the in-
structions of the system controller.
This IC also reads the adjustment data of the EEPROM
(IC905) and outputs the adjustment voltage from the D/A
converter (IC906 to IC911).

6-2. BC Board Descriptions

Carries out the switching of the switches on each board and
setting of DAC data.
1. Serial Communication with Boards
The system control CPU (IC1) carries out serial communi-
cation with the SUB CPU of each board inserted in slots us-
ing the 4 signals-MISO, MOSI, SCLK and SLOT NO. It regu-
larly receives abnormal detection signals from the power
supply circuit and deflection circuit, and information
(KILLER) for discriminating between color and black/white
for signals input from each input adapter. It chooses who to
communicate with using the signals SLOT-0 to SLOT-7.
2. Internal Signal Generation
IC104 to IC110 generates internal signals (PLUGE, 5STEP,
WHITE, GRAY, CROSS HATCH). The clock generated by
IC121 (525 mode:14.3181 MHz, 625 mode:14.1875 MHz)
is input to IC120 (sync generator) to generate the sync sig-
nal.
3. Character Generator
IC7 (character generator) is controlled to display the menu,
etc.
4. Parallel Remote Control
The input signal of CN5 (parallel remote control terminal) is
read by IC5 (I/O PORT EXPANDER).
5. ISR Terminal
The CPU (IC1) carries out communication with the ISR de-
vices via IC23 (serial control unit) and IC27 and IC28
(RS232C transceiver).
6. Serial Remote Terminal
The CPU (IC1) carries out communication with the remote
devices via IC22 (serial control unit) and IC25 and IC26
(RS485 transceiver).
7. Communication with Control Block
(HC Board)
The CPU (IC1) carries out communication with the control
block (HC board) via IC14 (RS422 transceiver), receives key
input information and the memory card reading data, and
transmits LED light information and the memory card writ-
ing data.
6-3